Concatenate images generated by mapshot (Factorio MOD)

mapshot-concat.sh

#!/bin/sh -ue

# mapshot-concat.sh map-xxxxxxxx/d-xxxxxxxx/zoom_x output.jpg

if [ -n "$WSL_DISTRO_NAME" ]; then
    # WSL1/2
    FACTORIO_DIR="/mnt/c/Users/$USER/AppData/Roaming/Factorio"
elif [ "$(uname -o)" = Darwin ]; then
    # macOS
    FACTORIO_DIR="$HOME/Library/Application Support/Factorio"
else
    # Linux
    FACTORIO_DIR="$HOME/.factorio"
fi

MAPSHOT_DIR="$FACTORIO_DIR/script-output/mapshot"

find "$MAPSHOT_DIR/$1" -name '*.jpg' -print |
sed -e 's/tile_\(.*\)_\(.*\)\.jpg$/& \1 \2/' |
sort -k3n -k2n |
awk -v "outfile=$2" '
    NR == 1 {
        xmin = $2
        ymin = $3
    }
    {
        print "\047" $1 "\047"
    }
    END {
        print outfile
        xsize = $2 - xmin + 1
        ysize = $3 - ymin + 1
        print "gm montage -mode concatenate -tile", xsize "x" ysize
    }
' |
sed -n -e '$!H' -e '${p;x;p}' |
tr '\012' ' '